Adjustable speed material handling device



March 14, 1967 P. F. MCADAMS ADJUSTABLE SPEED MATERIAL HANDLING DEVICEFiled Dec. 24, 1964 INVENTOR PAUL F. M ADAMS ATTORNEY United StatesPatent 3,308,976 ADJUSTABLE SPEED MATERIAL HANDLING DEVICE Paul F.McAdams, St. Joseph, Mich., assignor to Clark Equipment Company, acorporation of Michigan Filed Dec. 24, 1964, Ser. No. 420,972 5 Claims.(Cl. 214-140) This invention relates to fluid motors, and morespecifically to piston and cylinder type fluid motors havinginterchangeable speed control means and which are especially suitablefor use with material handling vehicles such as tractor shovels.

Ordinarily, a tractor shovel is provided with a bucket which ispivotally mounted at the forward ends of a pair of boom arms and isactuated between a loading or digging position and a carry position bymeans of one or more double-acting fluid motors which are connecteddirectly to the bucket and connected to the tractor shovel body or theboom arms. In a material handling vehicle such as a tractor shovel themaximum force required to actuate the bucket is the force required topivot the bucket with a full load from the loading or digging positionto the carry position. Once the maximum force which is required toactuate a fully loaded bucket from the loading position to the carryingposition is determined, then it is a simple matter to choose a fluidmotor having a piston area which, after substracting the cross-sectionalarea of the piston rod, will provide sufficient force for pivoting thebucket under normal operating conditions. Heretofore, a conventionaldouble-acting piston and cylinder type fluid motor has been used in suchapplications, and so the side of the piston opposite that to which thepiston rod is connected presents a greater elfective crosssectionalarea. As a result there is actually a greater force available forpivoting the bucket forwardly from the carrying position to a loadingposition than vice versa which, of course, is unnecessary. Thus, it isan object of my invention to provide a double-acting fluid motor whichhas a retracting force that is greater than its extending force.

Further, since in a conventional piston and cylinder type fluid motor alarger volume of pressurized fluid is required to move the piston so asto extend the piston rod than to move the piston so as to retract thepiston rod, the piston moves more slowly than when the piston rod isbeing retracted, assuming that the fluid flow remains substantiallyconstant. This is undesirable because in order to run such machineefliciently they should be operated as rapidly as can be done safely. Asa consequence, it is another object of my invention to provide a fluidmotor which has an extension speed that is greater than its retractingspeed.

A further object of my invention is to provide an improved fluid motorfor use as a bucket tilt motor.

Still a further object of my invention is to provide a double-actingfluid motor having readily interchangeable speed control means.

In carrying out my invention in a preferred embodiment thereof I providea fluid motor having a cylinder with an open end and a closed end. Apiston is slidably disposed in the cylinder and has a piston rodattached thereto which extends outwardly through the closed end of thecylinder. A removable cap is attached to the open end of the cylinder. Aspeed control rod is removably connected to the piston and slidablyextends through the cap.

The above and other objects, features and advantages of my inventionwill become more readily apparent to persons skilled in the art when thefollowing detailed description is taken in conjunction with theaccompanying drawing wherein:

3,308,976 Patented Mar. 14, 1967 FIGURE 1 is a side elevation of atractor shovel embodying my invention; and

FIGURE 2 is a longitudinal sectional view of a ferred embodiment of myinvention.

Referring to FIG. 1, the reference numeral 10 denotes generally atractor shovel which includes a body 12 supported by a pair of frontdrive wheels 14 and a pair of rear dirigible drive wheels 16, only oneof each being shown. Body 12 includes an operators station 18 and anengine compartment 20 within which the vehicle prime mover is located.Pivotally connected to body 12 on each side thereof at 22 is a pair offorwardly extending boom arms 24. Each boom arm 24 can be elevated bymeans of a single acting fluid motor 26 which is connected at one end toboom arm 24 at 28 and pivotally connected at 30 to a downwardlydepending bracket 32 attached to body 12.

Pivotally connected to the forward ends of boom arms 24 at 34 is abucket 36. Disposed on each side of body 12 and connected to bucket 36at 38 and to body 12 at 40 is a pair of bucket tilt assemblies 42, onlyone of which is shown. Referring now also to FIG. 2, each assembly 42includes a double-acting fluid motor 44 and tubular extension member 46.Fluid motors 44 are actuatable to pivot bucket 36 between the loading ordigging position shown in FIG. 1 and a carrying position in which theopen front of bucket 36 is substantially horizontal. Also, boom arms 24and assemblies 42 cooperate so that as boom arms 24 are raised toelevate bucket 36 the attitude of bucket 36 is maintained substantiallyunchanged, whereby spillage of any load from the bucket is minimized.

Each fluid motor 44 includes a cylinder 48 which is closed at one end bya cap 50. It will be appreciated, of course, that cap 50 may be integralwith or separate from cylinder 48. The other end of cylinder 48 isclosed by a removable cap 52 which may be threadably connected tocylinder 48 or bolted to a flange 54 which forms a part of cylinder 48.Slidably disposed within cylinder 48 is a piston 56 which forms withcylinder 48 and caps 50 and 52 a pair of fluid chambers 58 and 60.Connected to piston 56 is a piston rod 62 which extends outwardlythrough cap 50 and attaches at the outer end thereof to bucket 36 at 38as was explained hereinabove. Also connected to piston 56 is a speedcontrol rod 64 which extends outwardly through cap 52. As shown, pistonrod 62 extends through piston 56 and has a threaded portion 66 whichthreadably engages a cooperating threaded portion 68 in the adjacent endof speed control rod 64, whereby rods 62 and 64 are connected to piston56. It will be appreciated that cap 52 and rod 64 form speed controlmeans, an increase in the crosssectional area of the rod causing anincrease in the extension speed of the motor, which are readilyinterchangeable with other speed control means having a speed controlrod of different cross-sectional area. Cylinder 48 also is provided witha pair of fluid supply ports 70 and 72 which are located adjacent caps50 and 52, respectively.

It will be understood that various packings and other fluid seals areutilized in fluid motors 44, as required, although they have not beendescribed in detail. Also, it will be understood that fluid supply ports70 and 72 are connected to a source of pressurized fluid via suitablefluid circuitry which includes a control valve for directing pressurizedfluid to either one or the other of the ports or neither of them.

Turning now to the operation of my invention, it will.

3 fluid motors 44 through supply ports 7 so that pistons 56 are movedtoward the left as shown in- FIG. 2 to approximately the position shownin FIG. 2. At this point the open face of bucket 36 is substantiallyhorizontal. Now, by supplying fluid motors 26 .with pressurized fluidthe boom arms 24 may be raised in order to elevate bucket 36. As boomarmsv 24 are being elevated, assemblies 42' are cooperating with themthrough a parallelogram links age arrangement to maintain the open frontof bucket 36 substantially horizontal. The bucket may then be dumpedfrom the elevated position. In order to dump the bucket the operatoractuates the control valve for motors 44 to supply pressurized tochambers 60 through ports 72.'

As a result pistons 56 moves toward the right until the bucket ispivoted far enough to dump the load therefrom.

Because rods 64 have a greatercross-s-ectional area than rods 62, theforce available for dumping bucket 36 is less than the force availablefor rolling back the bucket fromthe loading or digging position to thecarry position. However, the bucket 36 may be pivoted forwardly to dumpmuch more rapidly thanit is pivoted back tothe carry position due to thefact that rods 64 cause the volume of chambers 60 to be less than thevolume of chambers 58; thus for a given amount of pressurized fluidsupplied from the vehicles hydraulic system the pistons 58 will movefaster to the right than to the left.

Although I have described andillustrated a preferred embodiment of myinvention, it will be understood by those skilled in the art thatmodifications may be made in' the structure, form and relativearrangement of parts, without departing from the scope and spirit of myinven- 1 tion. Accordingly, it should be understood that I intend tocover by the appended claims all such modifications 2. In a materialhandling vehicle; a boom arm pivotally connected to the vehicle; abucket pivotally connected to one end of said boom arm; and bucket tiltmeans connected to said bucket and the vehicle, said means including acylinder with an open end and a closed end, a piston slida'bly disposedin said cylinder, a piston rod connected to said piston and extendingoutwardly through said closed means for communicating fluid to saidcylinder at one side or the other of said piston, and interchangeablespeed control means, said speed control means including a cap removablyconnected to said open end and a speed control rod remova-blyconnectedto said piston and extending outwardly through said cap so that saidspeed control means may be interchanged readily withother speed controlmeans having a speed control rod with a different cross-sectional area.

3., A combination as set forth in claim 2 wherein said bucket tilt meansincludes a tubular extension member fixed to said cylinder and pivotallyconnected to the vehicle so that said member encircles said speedcontrol rod when said speed control rod is extended.

4. In a material handling vehicle,-material engaging means, means forraising and lowering the said material engaging means, and means formoving the said material engaging means back and forth between at leasttwo operative positions, the last-named means comprising a doubleactingpiston and cylinder type fluid motor and means for,

adjusting the speed of the said fluid motor for one direction ofoperation, the said fluid motor including a piston rod whichisconnectedto the piston of the said fluid motor and extends from one endof the said. fluid motor and the said means for adjusting the speed ofthe fluid motor including a speed control rod connected to the saidpiston and extending in the oppositedirection from the said piston rod.

5. A material handlingvehicle as specified in claim 4 in which the saidfluid motor includes a tubular extension member secured thereto andencompassing the said speed control rod.

References Cited by the Examiner UNITED, STATES PATENTS 676,251 6/1901Hagman 926 X 1,511,695 10/ 1924 Weitman 92-6 3,057,496 10/1962 Garske214 References Cited by the Applicant UNITED STATES PATENTS 394,31412/1888 Turner. 2,146,807 2/1939 Ferari. 2,668,631 2/1954 Reese.2,753,059 7/1956 Pilch. 2,782,946 2/1957 Hough. 2,783,903 3/ 1957Beyersstedt.

HUGO O, SCHULZ, Primary Examiner.

1. IN A MATERIAL HANDLING VEHICLE, A BOOM ARM PIVOTALLY CONNECTED TO THEVEHICLE, A BUCKET PIVOTALLY CONNECTED TO ONE END OF SAID BOOM ARM, AND ABUCKET TILT ASSEMBLY CONNECTED TO SAID BUCKET AND THE VEHICLE, SAIDASSEMBLY INCLUDING A DOUBLE-ACTING PISTON AND CYLINDER TYPE FLUID MOTOR,A SPEED CONTROL ROD CONNECTED TO SAID PISTON AND EXTENDING OUTWARDLYTHROUGH ONE END OF SAID MOTOR AND A TUBULAR EXTENSION MEMBER CONNECTEDTO SAID ONE MOTOR END AND CONNECTED TO THE VEHICLE.